1979 Annual report for EL 1444 Pine Hill

Abstract

A rare earth /uranium prospect has been discovered recently in the southern Anmatjira Range, to the north of the Pine Hill homestead, in the south of the Licence area. This has included office and fieldwork with the object of identifying the more significant airborne anomalies from the various airborne surveys, (Otter 1977, BMR 1976 plus an early undocumented BMR survey), and evaluating these anomalies in the field. A plan showing geology, anomalies and sample locations at a scale of 1;100,000 has been drawn up. For data sheets for anomalies and other sample locations together with an Assay Data Summary see the hardcopy of the company report. Additional bore water samples have been taken and analysed for uranium. Results for all bore water analyses in the Napperby/Mt Peake region, (which includes the Pine Hill License area), have been plotted on a 1:250,000 scale plan for the purpose of locating possible hydrothermal skarn uranium deposits in the Reynolds and Anmatjira Ranges and defining prospective targets for secondary uranium concentrations in Tertiary calcretes/carbonaceous sediments. Results following the 1977 airborne spectrometer survey are as follow; 41 anomalies were found. These did not include 2 anomalies reported from the earlier BMR radiometric survey. Of the 41 anomalies, 15 occurred over Quaternary alluvial sand and 26 on the granite or gneissic outcrop. Anomalies were investigated in a short reconnaissance trip in December 1978 none proved to be due to anomalous concentrations of uranium and thorium. However, two anomalous sources of radioactivity were found during ground traverses. N1-4; This sample was found amongst rubble on a steep scree slope. Background readings on the Scintrex BGS-ISL average from 60 cps to 150 cps, highly localised (up to 1 metre across), anomalous zones gave 1000 cps on the surface. Shallow pits gave greater than 10,000 cps (off scale). Petrographic and assay results show that the radioactivity Is due to uranium and thorium concentrations (1000 ppm and 6.3t respectively) in the mineral monazite, a rare earth phosphate. The monazite occurs as the dominant mineral in a monazite-garnet gneiss. The unit in which the monazite-garnet gneiss occurs appears to have a maximum width of 300 metres (air photo interpretation only). No field relationships are as yet known, as the anomalous rocks were found in shallow pits dug into a scree/rubble slope. Quartz-feldspar-biotite-gneisses outcropping nearby had a low count (less than 200 cps). N1-7,8; These samples were taken from the south-east of the range near anomaly PH-4. High radioactivity (750 cps) was encountered over a small detrital fan, surrounded by porphyroblastic feldspar-biotite quartz pencil gnesses. Deeply weathered chloritic schist at the bottom of a shallow pit gave 2000 cps on the BGS-ISL scintillometer. However, assay results showed that the radioactivity was due to the relatively anomalous concentrations of thorium in the schist and gneiss. The samples were not assayed for rare-earths, but the possibility of monazite in the alluvial fan, and surrounding lithologies cannot be ruled out, as sediment samples were not taken. Bore waters were sampled where possible, and assayed for uranium. The Pine Hill Stock Bore is directly downstream from the monazite occurrence at N1-4, so its anomalous value of 720 ppb U in the ground water may be due to leaching of relatively extensive deposits of monazite, or other uranium rich mineral assemblages in this area. The low U content in the waters of the Home Bore, in the same drainage channel, does not reflect the uranium concentration in the ground-waters, as it is a shallow well collecting subsurface stream waters. Sandy Creek Bore downstream from Pine Hill Stock Bore gave a lower, but still anomalous, value of 430 ppb U. This indicates dilution by uranium-poor waters running off the Anmatjira Range, between Pine Hill Stock Bore, and Sandy Creek Bore. Hawk's Nest Bore gave the anomalous value of 310 ppb U, but this may only represent leaching from the high uranium-content granites of the Reynolds Range, rather than leaching or precipitation of a uranium body of economic interest. Bore water results are shown on the enclosed plan.